Post-Embryonic Development of the Horseshoe Crab

Abstract

Individuals of Limulus polyphemus and Tachypleus tridentatus reached, respectively, the fourteenth-instar and tenth-instar stages during our nine-year rearing experiment. Body sizes were measured using exuviae and body specimens. The results made their growth steps clear, and body sizes of the juveniles at further growth stages could be estimated. We conclude from these data that L. polyphemus males generally molt 16 times to reach maturity in the ninth year; females molt 17 times to reach maturity in the tenth year. Similarly, we conclude from the presumptive numbers of growth stages that T. tridentatus males generally molt 1 5 times to reach maturity in the thirteenth year; females molt 16 times to reach maturity in the fourteenth year. Although we have few data on growth stages of Tachypleus gigas and Carcinoscorpius rotundicauda, it is thought that T. gigas males molt 12 times to reach adulthood, females molt 1 3 times, and that C. rotundicauda reaches maturity after the thirteenth molt in both males and females.

Enhanced growth of juvenile Tachypleus tridentatus (Chelicerata: Xiphosura) in the laboratory: a step towards population restocking for conservation of the species

“…Therefore, with the exception of the telson, the shape of horseshoe crab at different developmental stages is similar. This is consistent with the results obtained by Sekiguchi et al (1988) on T. tridentatus and Limulus polyphemus. An increase in the wet weight with the prosomal width was isometric (b ≈ 3) in the present study.…”

“…The present study showed that the growth of Tachypleus tridentatus could proceed throughout the year, provided that the seawater temperature was optimal (28 to 30°C). A much slower growth for T. tridentatus, however, was obtained by Sekiguchi et al (1988). In the first year of rearing, the juvenile T. tridentatus remained as 1st instars when reared at room temperature but developed into 2nd instars when reared at 30°C.…”

“…Goto & Hattori (1929) suggested that Tachypleus tridentatus molts 12 to 13 times before maturity, while Kawahara (1984) proposed that males molt 14 times in 9 yr and females 15 times in 10 yr. Sekiguchi et al (1988), on the other hand, reported that T. tridentatus males molted 15 times within 14 yr, based on an allometric growth pattern identified in laboratory culture over a period of 9 yr. Asano (1942), however, reported that the species reached maturity in 15 to 16 yr after 17 or 18 ecdyses based on field observations and measurements of exuvial sizes. To follow individuals' growth from hatching to maturity in a natural habitat is challenging because it is impractical to produce a long-lasting external tag for juvenile horseshoe crabs due to their regular ecdyses , Lee & Morton 2005.…”

“…Such differences might be attributed to differences in rearing conditions, such as living space and water quality. Juveniles in the present study were maintained in a container (200 × 100 × 25 cm) much greater in size than those used in the study of Sekiguchi et al (1988), in which the size of containers varied from 3.4 × 3.4 × 3 cm to 36 × 25.5 × 10 cm, depending on the size of the juveniles. In addition, aerated seawater was used in the present study and the water was re-circulated.…”

POPULATION STRUCTURE AND MORPHOMETRY OF HORSESHOE CRAB Carcinoscorpius rotundicauda, Latreille 1802 IN KAMPUNG GISI COASTAL AREA OF BINTAN BAY OF RIAU ISLANDS PROVINCE

“…Dugaan ini sejalan dengan temuan Ehlinger and Tankersley (2004), bahwa salinitas yang tinggi dapat memperlambat pertumbuhan belangkas. Demikian pula hasil penelitian Sekiguchi et al (1988), bahwa pertumbuhan belangkas menurun secara signifikan dengan meningkatnya salinitas.…”